About fifteen of us were gathered in a classroom one Thursday evening last month on San Francisco's South Bay. We were there to hear a talk as part of a bat banding workshop and field demonstration at a riparian restoration site. The wildlife ecologist and bat expert who gave the talk explained why the nocturnal creatures deserve our protection and respect. In the field the following night, we watched our teacher wade chest deep across a creek, deftly extract a tiny bat from a mist net by the light of his headlamp, and measure, observe, and band it back at our camp. As I watched, I imagined what it would be like to be a scientist who gets to study and protect these fascinating animals every day, and I wondered if there was a way for a non-scientist like me to get involved. Then I learned about Bat Detective, an online citizen science project that allows volunteers from around the globe to help scientists identify bat calls from recordings taken at locations throughout the world. Currently, one in five mammals is a bat, and one in five species of bats is threatened with extinction in the next 50 years. Bats are at risk for a number of reasons. They usually only have only one offspring a year, so a premature bat death can have a significant impact on the population. Bats have lost a large portion of their habitat, and many are vulnerable to climate change and other health and environmental disruptions, such as White Nose Syndrome in North America. While scientists are using bat banding and other field techniques to study these flying mammals, much more needs to be done. To help scientists develop ways to conserve bats, for the past decade citizen science volunteers with the organization iBats have recorded night sounds in the field at locations throughout the world. Bat Detective was developed three years ago at University College London—with partners at Bat Conservation Trust, Bat Life Europe and the Citizen Science Alliance—to assist iBats by bringing together volunteers who can help identify bat calls in these iBats recordings. To participate, volunteers can visit the Bat Detective website, go through a tutorial, and then listen to recordings to decipher bat sounds form other night noises. Bats use high frequency calls to locate prey and lower frequency calls to communicate with one another. Often these sounds are too far out of range for people to hear. So iBats participants used special time-expansion bat detectors to make the recordings so people can hear and identify them, said Rory Gibb, a Bat Detective scientist at the University of London. During the past three years, scientists have uploaded a small percentage of these iBats recordings onto the Bat Detective website and invited citizen science volunteers to listen to the recordings and identify the bats they hear. Since 2012, more than 4,000 volunteers with Bat Detective have explored 94,000 audio snapshots (a small percentage of what has been collected) and identified more than 11,000 bat calls. While most of these are search calls, a smaller percentage is social calls as well. This month, Bat Detective kicked off a “World Tour” and is uploading exponentially more bat sounds from different parts of the globe that volunteers can help analyze. All of this analysis will be used to create machine-learning algorithms for automated software that will be able to reliably detect bat species for bat surveys in the future, Gibb said. The data will help scientists, like the one I met during the bat banding demo, better understand and protect the more than 1,000 bat species that control insects, re-vegetate rain forests, and play other important roles in ecosystems around the world.